Conventionally, finite element models have been used to simulate a rotating tire, in order to acquire a contact length or distribution of deformation (deformation shape) on a tire circumference at a tread portion of the tire. In such acquiring methods, however, because of the time required for preparing finite element models as well as required for simulation computing, it has been difficult to obtain the deformation shape of the tread portion or the contact length in a short period of time. For this reason, the contact length and the deformation shape of a stationary tire has been used as substitutes for those of a rotating tire.
However, in consideration that the deformation shape on the tire circumference affects the contact length and the contact region contour, and therefore has a significant effect on the tire performance, there has been a need for acquiring the contact length and the deformation shape that are measured with the rotating tire in order to determine the tire performance accurately.
The following Patent Documents 1 to 3 disclose, for instance, a method in which an acceleration sensor is attached to a tire to acquire measurement data of acceleration of the tire during rotation, and from the acquired measurement data, power spectrums and vibration spectrums are obtained to estimate the status of the road during the tire rotation, and a method in which a timing at which a tread portion is in contact with a road surface is determined from measurement data of acceleration in a radial direction.
However, any one of the Patent Documents 1 to 3 does not allow the deformation shape and the contact length of a rotating tire to be calculated from the measurement data of acceleration, though it is possible to estimate the status of the road surface using the measurement data.
Patent Document 1: JP 2002-340863 A
Patent Document 2: JP 2003-182476 A
Patent Document 3: JP 2002-511812 A